Joh Mylrea was born in Douglas and educated there at the Athole Academy. He then became a student for the Manx Bar and was admitted in 1871, and a few years later to the English Bar. However he never actively followed this profession being more interested in the arts and music. He was also a splendid linguist.
In 1881 he was elected to the House of Keys for Garff and represented this sheading until 1900 when he transferred to Douglas North. He was by far the most graceful speaker in the House, his oratorical efforts being marked by an ease, polish, and finish which none of his contemporaries in the Legislature could approach, and which make present-day politicians look very small. He was a slightly liberal Conservative. He was narrowly defeated in becoming Speaker of the House of Keys in 1898 by Arthur William Moore.
Mr Mylrea was also an active but not so successful businessman, being a director of Dumbell's Banking Company and Isle of Man Tramways Company and also the Chairman of the Isle of Man Steam Packet Company. He was also quite involved with the development of the Electric Tramways from Douglas to Laxey and Ramsey, and from Laxey to Snaefell summit. However he left the Island soon after the failure of Dumbell's Banking Company and died abroad in Scandau, Germany.